The Park Tool WAG-4 comparatively measures the distance from the rim to end of the hub locknut on each side of the wheel. One can then accurately dish the wheel so that the rim lies in the center of the hub. This is especially difficult to eyeball on rear wheels or disc wheels where the rim does not center between the hub flanges. Compatible with 16 Inch to 29 Inch wheels (ISO 305 to 630). Can even be used with tires still mounted. Made in the USA.
Another great park tool
